Civilians caught in the conflict. Let's turn right now to Jonathan Karl tonight. Reporter: If confirmed, it's not the first time a commercial airliner has been caught in the crossfire of a conflict, killing hundreds of innocent civilians. It's not the first time the white house has had to detail with the consequences. It looks like it may be a terrible tragedy. Reporter: On July 3, 1988 a missile fired from a U.S. Navy ship brought down an Iranian airlines as it flew over the persian gulf. The uss vincennes has been exchanging gunfire that day and mistakenly miss took it for a fighter jet. Five years before that in September of 1983, a Russian jet fighter shot down a Korean plane with 269 passengers on board, the 747 had accidently strayed into then soviet air space. One of the passengers was a U.S. Congressman. The soviet government first denied involvement and later claimed the plane was spying on them. The similarities are very strong. In both of those cases there had been something else going on in the area the day before. So it's possible that people on both sides of the border, Russia and Ukraine, were thinking this was not a passenger plane but thinking it was a military plane. It's important to get to the bottom of this sooner or later because the possible repercussions that can flow from this beyond the tragic loss of life. Reporter: As tragic as that loss of life is as you heard from vice-president Biden there, the concern here in the white house is that what happens next could be even worse if those repercussions could include a much wider conflict. As was the case with both the downing of that Iranian passenger jet and the Korean passenger jet in the 1980s, what you're about to see, David, is some very high stakes diplomacy. Concern about the ripple effect around the world. You and I were talking about the black boxes earlier, a tug of war, those who recovered it saying they would turn it over the Russia. There's also concern about tampering with those black boxes? Reporter: Look, there was a firm statement out of the white house today saying that all that evidence needs to remain on Ukrainian territory, should not be touched, should not be tampered with until international investigators have been able to get on the ground and have been able to conduct on investigation. The concern right now, David, is that that territory is effectively in the control of Ukrainian pro-russian rebels and that those, as you've heard them directly say, Martha Raddatz reporting, they are claiming they've already found the black boxes and have shipped them off to Russia. U.s. Officials don't know if that's actually true but the message to Russia is leave all of that material, all of the evidence in Ukraine until international investigators are able to look at it first. That's the big question, have they been shipped already. Jon Karl, our thanks to you. Of course today's disaster in

This transcript has been automatically generated and may not be 100% accurate.

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